I started out to install Slackware on a flash drive.  It was fairly easy to step
through the menus to install it.

Two issue came up.
1.  The partition was not showing up after the init sequence.
2.  /sbin/init was not mounting.

Solution.

1. Add -w 10 in the initrd string to add a 10 sec. wait time before booting the init
2. Add 'usb-storage' after the -m for Modules

mkinitrd -w 10 -c -u -k $(uname -r) -f ext4 -r "UUID=875b0f2d-ab71-4d5e-873b-788e4efabc84" 
-m usb-storage:xhci-pci:ehci-pci:xhci-hcd:uhci-hcd:hid:hid_generic:hid-logitech:hid-logitech-dj:
hid-logitech-hidpp:hid-lenovo:hid-microsoft:ehci-hcd -o /boot/initrd.gz

Minor issue:

Get wicd connection manager to start without logging in.

1. vim /etc/initd./start-wicd.sh
     #!/bin/bash
     /etc/rc.d/rc.wicd
2. sudo ln -s /etc/init.d/start-wicd.sh /etc/rc.d/
